Tread



P. W. DALRYMPLE.

TREAD.

APPLICATION FILED APR. 12. I919.

Patented July 20, 1920'.

2 SHEETS-SHEET l.

P. W. DALRYMPLE.

TREAD.

APPLlCATlUN mm APR, 12. 1919.

Patented J My 20, 1920.

2 SHET$-SHEET 2.

IHILIP W. DALRYMPLE, OF BALTIMORE, MARYLAND.

TREAID.

Specification of Letters Patent.

Patented July 20, 1920.

Application filed April 12, 1919. Serial No. 289,707.

To all icimm it may concern:

Be it known that I, PHILIP W. DALRYM- ILE, a citizen of the United.States of America, residing in the city of Baltimore, State of Maryland,have inyented certain new,

and useful Improvements in Treads, of

which the following is a specification.

This invention relates to a vehicle tread having the advantages that thetread pressure is equalized without regard to the va riations of thesupporting surface and full traction by each tread member is maintaiued,it accommodates itself absolutely to all irregularities of the surfacetraversed without a 'ipriwiuhly raising, or lowering the main body ofthe vehicle and without inrportant change of level or attitude'of thevehicle, due to such irregularities, which are to be distinguished fromgeneral changes of contour, encountered'un ascending and descendingsteep inclines.

The mechanism is of the belt type, having a plurality of feet moved in acontinuous path by an endless belt or chain'rnember. These feet aremounted each on a separate frame or leg, one for each foot or tractionmember, and in addition to the driving means, each such leg or frame iscontrolled by means imparting to the tread a combination of rigid andflexible resistance by which the weight of the vehicle is supported anddistributed, and uniformity of pressure on the feet or traction members,in contact with the surface being traversed, is attained without regardto even the most abrupt irregularities. v

To this end the individual frames or legs controlling the feet arenotonly carried in contact with a rigid guide on a fixed continuouspath, but are also controlled as to their position relatively to saidpath and guide by a flexible distributing belt which engages each leg ata point spaced from the point on that leg engaged by the guide so thatit impartsto the leg a tendency to swing relatively to the guide intothe position in which it engages the road and supports its share f theweight, e., the feet in a. position to engage the road have a uni formtendency to swing downward so that each will support the same weight,and as any foot is forced upward from this lowermost position byencountering a. projection on the -road, it imparts to this flexiblememher or belt a temporary increase oftension which has the effect offorcing or tending to force the other feet, which are likewise inposition to engage the road, downward, so that they raise the wholemachine slightly, causing it to proceed at an elevalion corresponding tothe average elevation of the ground under it, without beinp undulythrown up from or dropped below its course by abrupt irregularities ofsurface.

A vehicle equipped with this type of trend can be driven over a veryrough road bed or in open, rough or soft country where there is no road,at a fair rate of speed with :1 minimum effort and without serious shockto the vehicle or its load, and it can be used under these circumstanceseither for carrying, towing or plowing, or other farm work.

T he drawings show a single pair of closed tracks or guides. In thevehicle equipped with the tread,there is. such a pair of tracks on eachside of the machine, the two pairs being situated in vertical parallelplanes. Rollers attached to each leg run on the tracks 01' guides andare moved over these tracks and maintained in their relative spacing bycables wnich run over sheaves at the ends of the elongated loops formedby the tracks or guides. Each leg has a set of puL leys, in addition tothe rollers bearing on the tracks or guides, the pulleys being engagedby the tensimi cable or cables. The tension pulleys are spaced from theaxis of the leg, whiclr is also the axis of the track following roller,and in normal position of each leg when its foot is in Contact with theground, the tension roller is almost directly over the foot, so that thethrust applied by the tension cable is effective directly downwardagainst the support, the legs being pivoted in the axis of the trackfollowing rollers and controlled by the cables which impart downwardthrust to them when they are in contact with the bearing surface, thethrust being equal in the instance of each foot which is in operativeposition.

The vehicle runs on rollers supported by stationary feet and engaging asmooth traclgthe feet being arranged to compen sate all irregularitiesin the roadway and the weight being equally distributed over all thefeet which are in hearing or supporting position, so that unevenroadways ahd hroken ground are no obstacle to the transportation ofgreat weights; and the distribution of the load on the road bed lessensthe Wear and tear on the surface. The power required is the minimumbecause of the distribution of the weight over a number of points ofsupport with an equal and hence small load on each point of support, andthe correspondingly slight depression of the ground, and becausedissipation of energy on account of shocks and jars is also elimlnated.The necessity of using cushioning means in the form of springs or tiresis at the same time dispensed with.

Referring to the drawings,-

Figure l is a side elevation of the tread as applied to one side of avehicle.

Fig. 2 is a detail of a portion of the same with parts broken away forconvenience of illustration.

Fig. 3 is a side view of one of the legs or foot supporting framesdetached.

Fig. dis a section through the frame as on the line 4, 4, Fig. 1,showing one of the leg and foot members in elevation approximately inthe attitude in which it is shown in Fig. 3.

Fig. 5 is a diagrammatic end view.

Referring to the drawings by numerals, the illustration relates to asingle tread with the cooperating parts to be applied to one side of avehicle ortractor, it being understood that both sides of the vehicleare similarly equipped in this regard; in other words the illustrationcorresponds to one drivingwheel of a vehicle as an automobile, thelogical, ifnot the essential arrangement being that the other side ofthe machine be similarly equipped.

Referring particularly to Figs. 1 and 4, the illustration includes twoparallel tracks or guiding members 1, which in the device illustrated,are formed on the peripheral edges of two parallel vertical plates 10.These plates are maintained in rigid relation by transverse braces 11which also support, intermediately of the plates, a limiting or stopguide 12. The plates 10 and more particularly the tracks 1 carriedthereby, are of horizontally elongated shape, being provided near eachend with a suitable bearing 13 for a horizontal transverse shaft 14. Theends of the track adjacent these shafts are formed on' circular arcsconcentric with the shafts, and one or both shafts, preferably the rearshaft 14, is suitably driven from the source of power with which thevehicle, whatever it may be, is equipped, the driving means and sourceofpower not being shown.

Mounted on each shaft 14' between the plates 10 and suitably spaced fromeach plate. as hereinafter described, are two sprockets 15, such ofthese sprockets as are to be used for driving purposes being rig idlysecured to their shafts, the front and rear sprockets on each side beingin alinement. Over each sprocket is passed a belt, chain or cable 16. Inthe see particularly 'Fig. 4;, this is a double cable,

resent instance,

that is, two parallel cables side by side, provided at intervals withbar-links 17 secured thereto for engagement by the sprocket teeth, andthe sprockets are suitably grooved and notched or toothed to receive thesame. Between the bar-links 17 which as shown span the two cables ofwhich each single belt is composed, are hearing blocks 18, similarlyspanning the cables of each belt. Each block includes a bearing for atransverse shaft 20 which shafts are carried by corresponding blocks ofthe two belts, the shafts extending from the outside of one plate 10 tothe outside of. the other plate 10. To each block the cables forming thecorresponding belt are secured by means of clamping bars 21. Both thecross-bars 17 and the blocks 20 cooperate with the sprockets 15, theperipheral surfaces of which are provided with transverse notches 22 toreceive the corresponding links 17 and chambers 3 for blocks 18. Thelinks 17 are engaged by the notches 22 to drive the belts, and chambers3 are preferably made to admit the blocks 18 with a considerableclearance so the blocks, or rather the wheels 23 on their respectiveshafts are free to follow the track 1. The shafts 20, referred tohereinafter as the wheel shafts, are provided each with two rollers orwheels 23, one near each end of the. shaft and mounted to roll upon andfollow corresponding tracks 1 on the peripheries of the plates 10. Theserollers should rotate freely on the shafts.

Each. shaft 20 also carries a corresponding frame or leg 25. Each suchframe or leg consists of radial or traction arms 26 and tangent orsupporting arms 27. Seen in elevation from either end of the machine,the traction arms 26 are spaced apart at the shaft by a distance equalto the distance between the inner faces of the rollers from which pointthey extend parallel for a little less than half their length, when theycon verge to their extremities at. an angle of about 30, where they arespaced in the formof the machine shown by a distance a little more thana third of that separating their upper extremities. The tangent andsupporting arms 27 of each leg are also connected at one end to thecorresponding shaft 20 from which, considering the legs in bearingposition as hereinafter' described, they extend backward at an angle ofpreferably from 60 to 90.with; the radial or traction arms 26 for adistance equal to about twothirds the length of the latter, at whichpoint they are bent downward at any preferred curve or angle, crossingthe radial or traction arms near their extremities. The portion of eachsupporting arm beyond the curve is substantially tangent to an imaginaryare drawn about the shaft at this point. Looking at the framcin front orrear elevation, i. e., in the direction of the length of level at thispoint is desirable.

the machine, these arms are joined to the shaft, each immediately on theinner side of one of the blocks 18 from which point they converge towardthe bend 28 until they are spaced by about one-half the originaldistance, from which point to their extremi Neer their ties they areshown as parallel. lower extremities they cross the radial or tractionarms 26 to which they are secured by a. foot plate 2:19 which is bentaround the ends of the arms or members and given a shape considered mostsuitable to the best result in bearing, power, traction, etc.

In addition to the rollers or wheels 23, each shaft 20 carriesintermediate of the arms 27, two grooved pulleys 30. These pulleys arealined with the space between the parallel portions of the hearing ortangent members 27. The tangent members or arms 27 also carry justbeyond the curve :28, between the parallel portions of these arms and onthe tangent portion, two grooved guide pulleys 31 mounted on a pin orjournal 32 which extends through both arms or its otherwise secured, andcooperating with these pulleys is a. suitable hearing roller 33 alsomounted between the arms on a suitable pin 34.

The feet and legs are carried by the cable bells It; about the track 1in counterclockwise direction as viewed in Fig. .l, the posh tion of upoint in each leg 25 in alinement with the axis of a shaft 20 beine'determined by contact of the wheels or rollers 23 with the trucks 1.This is what is termed the rigid element of the control or ectuatioin ofthese arms.

In addition to the cable belt 16, the tree d includes another belt orpair of cables 35, which, referring to the legs of feet which are incontact with the ground, are passed under the pulleys ill} on the shafts20 and over the pullers ill on the tangent portion of {he supportiiu;arms of the trams. This l5: the (llStlillllllIijI member or sul'iportingbelt which llllPHlh-l the flexible element to the resistance by whichthe weight of the vehicle is distributed and applied uniformly to thedifferent feet or traction members in contact with the surface bcin!traversed. it will be noted that as illustrated, the top or returnportion of the track is flat, straight and tangential with the circularends, so that the feet in returning extend no further into the machinethan iieccssuly to'accomplish the result. The bottom portion of thetrack is shown as curvedupward at the ends to bring the feet graduallyinto contact with the road. and to raise them gradually and pruticallyflat cei'itrallv. as no change of The air plicunt s invention is not,however. limited to any particular shape of the track. The limiting,quiiilc or stop 12 is intended to contact withlhe retaining rollers 33to limit tively to their axes 37,

the swing of the legs and to prevent the feet from being jammed orbroken by contact with each other or with the cable or pulleys, and toprevent breaking of the cable, etc. The manner of operation of thisguide is apparent. When any le. has reached the limit of its swing, theroller 33 carried thereby, engages the rigid truck 12 which is placedonly above the rollers in Contact with the ground, thus limiting andstop ing the upward swing due ll elevation.

The vehicle to be equipped may be supplied with any suitable number ofthe treetion elements or treads, as shown, in any suitable arrangementor combination.

In operation one or both of the shafts 14 carrying the sprockets 15,preferably the rear one, is driven by suitable connections, not shown,from a source of power carried by the vehicle. Rotation of the sprocketsengaging the blocks or cross-bars l7 and 18, moves the chain or belt incounter-clockwise direction about the continuous trucks 1, causing thewheels 23 to roll in contact with this surface. This action imparts acorresponding traverse to the legs 2:") with the feet 29 which arecontrolled as to their position relasee Fig. 3, by the tension ordistributing belts or cables 35. These cables 35 are passed around thepulleys 36 on the shaft 20 and the pulleys 31 on the tangent portion ofthe supportin arms 27, engaging the outer surface, '5. 6., the surfaceremote from the frame of the pulleys 30 and the inner surface, 2'. 6.,the surface toward the frame of the pulleys 31, tend to swing the legsoutward from the frame or track. This yielding or resilient tread of thefeet 29 is accomplished in part by means of the continuous cables orbelt 35 as follows:-In mounting and threading the cable or belt throughthe pulleys a suflicient amount of cable is allowed to give the flightof legs or feet the desired vertical motion, or are of swing about theiraxis of rotation 20. This plus the proportional amount of elasticity ofthe cables, (which would be determined by the load or weight of thevehicle and the size of the cables), permits the flight of legs or feetto adapt themselves to practically all or any of the irregularities andvariations of the ground. roadbed or supporting surfzu'rc. Preferablythe distributing belt 35 extends entire] around the track engaging thecorresponding rollers on all the legs of one set or tread, though thismight be differently arranged. As there is no resistance offered to theswing; of the an s on the upper side of the track and the thrust oroutward swinging tendency is unifomi, the feet and legs take a uniformposition relatively to the track as illustrated in Fig. 1 during thereturn stroke, but the important effect of this equalizing member takesplace to any hummoc or upon the working or supporting members or theseries of feet. It being assumed. that the surface, road or grouni'lbeing traversed une\ en, such of the feet as register with them are freeto settle down into hollows and others are placed upon the elevations orhummocks. The problem encountered is to make the bearing thrust uniformso that there is no considerable vibration or up and down motion of themachine, and no deep digging or indenting of the soil. The distributionof the weight carried or the weight of the machine with its load amongthe feet in position to bear upon the road surface, is due to the factthat all the feet are controlled by a member, the belt 32, which appliesequal tension and thrust to each. \Vhen any foot encounters a slightelevation or hummock, it is forced upward. relatively to the other feetand caused to rotate in lei'thanded revolution about its axis, or moreparticularly, about the corresponding shaft 20. Such rotation swings thefriction member or pullev on the leg upward transversely to the traclrand to the general tendency of the belt 35. This transverse motion,until it is equalized, causes a corresponding downward thrust on theother feet. This raises the vehicle very slightly as a. result of thecontact of one or more of the feet with the hummock suggested and causesit to move at an elevation corres onding, not to the raised or highestpor' tions of the road bein r traversed, but to he average elevation.therwise described, the effect is that the vehicle carries a series orset of supports or trusses, each with. a. suitable foot supplying thenecessary bearing power, and as it progresses. these trusses are set upon the ground to be traversed in. such a way as to have the tops orsupporting points of the trusses arranged substantially in a horizontalline. Each of these supporting members presents an aiiti-frivtion rolleren ing the track 1, and the vehicle carriiul in a line which correspondsin a generid way only to the road contour by the contact of freelyrotating rollers with a smooth track, :30 that we have the effect underall conditions oi' a vehicle moving by rolling contact on a track, andthis ellect is produced even though the ground actually traversed issoft or broken, and wholly impassable by wheeled vehicles.

It will be particularly noted that the treetion members 6 in allinstances when the corresponding legs are performing the working orlower stroke, are turned backward in the direction from which thevehicle is moving, giving a traction or forward thrust di rectily fromthe corresponding follower to the ground while the correspondingsupporting arm 27 is substantially vertical, transmitting its portion ofthe weight of the vehicle from the tension belt direct to the road. Asthe tension of the belt must be ternately around the uniform or nearlyso, the supporting thrust of each foot in the working stroke must benearly equal to that of the others. The up-' ward or yielding swing ofeach leg is limited by the stop or guide 12, and its downward swing bythe position oi the equalizing belt 35 or rather the rollers 30. Therollers 33 act both as retainers for the belt and as stops, the rollers40 merely as retaining members.

I have thus described specifically and in detail a single structureembodying my invention. in order that its nature and operalion may beclearly understood. However, the specific terms herein are useddescriptively rather than in their limiting sense, and the scope of theinvention is defined in the claims.

I claim- 1. A belt tread consisting of a continuous track or guide, aseries of followers on the track, a tension member connecting thefollowers, legs pivotally connected to the re speetive followers, a footon each leg, and a flexible tension member engaging each leg at a pointspaced from its pivot, applying an equal downward thrust to each foot ofthose engaging the surface being traversed, per mitting the feettoconform to irregularities of said surface substantiall 1 without variation of thrust, and means for moving the tension member and the trackfollowers around the track.

A belt tread, consisting of a continuous track in a vertical plane, aseries of followers spaced at intervals around the track, a continuoustension member connecting the followers, legs, each carrying a foot andconnected to the respective followers to swing therefrom, each leghaving engaging means spaced from its follower to be engaged by atension member, the followers being provided with corresponding engagingmeans, and an equalizing tension member passed alternately around theengaging means on the followers and around the opposite side of theengaging means on the leg, applying sub stantially equal thrust to alllegs engaging the surface being traversed without regard to the contourof said surface.

3. A belt tread, consisting of a continuous track in a vertical plane, aseries of followers spaced at intervals around the track, a continuoustension member connecting the followers, legs, each carrying a foot andconnected to the respective followers to swing therefrom, each leghaving engaging means spaced from its follower to be engaged by atension meniber, the followers being provided with correspon ilingengaging means, and an equalizing tension member passed alengaging meanson e followers and around the opposite side of the engaging means on theleg, applying substantially equal thrust to all legs engaging thesurface bein traversed without re ard to the contour of said surface,and means for limiting the swing of the legs.

,4. In a tread, a series of feet a separate leg for each foot, means formo 'ng a single point on each leg on a continuous path, the legs beingfree to swing relatively to said path, and means for departing uniformbearing pressure to all said feet which are in Working position withoutregard to the contour of the surface traversed.

5. in a tread, a series of sup 'iorting frames or leg members, eachcarrying a foot at one extremity, means for moving one point on eachsaid leg member in a continuous path relatively to which each leg isfree to swing about said point, engaging means on each said leg spacedfrom said point by a suitable lever arm, the spacing being in anapproximately horizontal direction in the instances of those feet Whichare in working position, a tension pulley for each foot, also moving insaid path, and a flexil'ilc tension member f0 applying, downward thrustto the feet which are in working position, making the bearing pressureof each foot on the road. equal without regard to the contour of theroad, said tension member being passed around the respective tensionpulleys and alternately and oppositely around the engaging means on theswinging legs.

6. In a tread, a series of leg guiding means near one extremity of eachsaid frame, a foot near another extremity, means for movingthe pivotedextreinit s: on a continuous path, a tension pulley for each foot alsomoving in the same continuous path, an. equalizing tension member. eu--gaging means for said tension. member on each said frame near the thirdextremity thereof, the tension member being passed over said means oneach leg which is in working position and under the tension pulley incorrcspomlin position, so that in the case of each leg in workingposition, a substantially direct downward thrust in'iparted to the foot.

7. In a tread, a series of leg frames, the individual frames having' abearing on which they are mounted to swing. means carryii'lg saidbearing on a continuous path in a vertical planc. a foot for each leg.the leg: frame including radially extending n1cmbers for supporting? thefeet. and moans also supporting the feet at an angle to sail?! radialmembers and normally approa h in; thrvertir'al when the corrcspondiin:foot in operation, an anti-friction member on each said vertical monibcrabove the foot, on anti-friction mciuber for each foot moving in acontinuous path, a flexible tension member extending alternately aroundthe anti-friction members in the continuous path, and the antifrictionmembers on the vertical members when the legs are in operation impartingan equal downward thrust to each foot in the bottom part of the path.

8. In a tread, a series of leg frames, the individual frames havingabearing on whi h they are mountcd to swing, means carrying said bearingon a contiluious path in a. vertical plane. a foot for each leg, theleg, frame including radially extending members for suppijirting thefeet, and means also supporting the feet at an angle to said radialmembers and normally approaching the vertical when the correspondingfoot is in operation, an anti-frietion member on each said verticalmember above the foot. an anti-friction member for each foot m'ovcontinuous ath. a. flexible tension member extending a ternatcly aroundthe anti-friction members in the continuous path, and the anti-frictionmembers on the vertical members when the legs are in oper ationmparting'an equal downward thrust to each out in the bottom part of thepath, pcrujtting the feet to yield and change tlieirjrelationsubstantially Without change of new.

1 in 2: tree d, a continuous guide or track, folilou'crs. and means formoving the fol lowers about the track, legs carrying feet pivotal]connected to the followers, each leg conasting of a traction member anda supporting member, anti-friction members carried bv the supportingmembers of the .iuiri'riction nien'ibers carried by the en; folloucrs.and an equalizing tension menu her pus l alternately and omnisitelyaround the anti-friction members carried lJj fllr followers and theanti-friction members carri d by the supporting: members.

lo. 1. lreud consisting of a track or guide, followcrs on the track orguide and means for moving the followers along the same, legs (HR'iTlllQfeet mounted on the followers to swing relatively thereto. the legsconsisting of radial members sharply in clincd duriin, their operativetraverse in the direction of motion of the followers relativcly in thetrack, and supporting members which under the same conditions aresubstantially vertical, the traction members and supporting membersconverging near the feet, and means For applying substantially cqualdmvnward thrust to all the supporting nnlnibcrs in the operative portionof the traverse and permitting them to yield to conform toirregularities of the road surface.

ll. .l belt trend consistii'ig of a track or gruiilc. fo lowers on thetrack or guide and means for moving the followers along the same, legscarrying feet mounted on the followers to swing relatively thereto, thelugs rousisting' of radial members sharply inclined during theiroperative traverse in the rlireetinn ml motion ut the followersrelatively tn the trnrk, 11ml supporting mem hers whirh umler the sameumulitinns: are sulwztantially rertiuel, the tract mm memhere aunlsupporting; members mnverging near the feet miti-l'iirlimi means("art-led by some iii the fullmvers, :mtiirivtlnn 1119mm carried by thesupporting members, and a flexible tension memher l alternately andoppositely uheiit the zinti 'i'riutien means an the followers, and theanti-friction means on the sumwrting members applying supportoperativepermitting them to yield to comof the road surface without substantialvariation of the hearing puwer of the feet.

Signed by me at Baltimore, Maryland,

1919. \V. DALRY of hlareh, PHILIP Witnesses ZELLA 'UHN, EMMA WEHMEYER.

this l day MPLE.

